1. Field of the Invention
The present invention relates to a backlight unit including light emitting diodes (LEDs) as light source, and more particularly, to an LED backlight unit in which the entire LED driver supplying a drive power for driving LEDs is embodied by one drive board.
2. Description of the Related Art
In general, since a cold cathode fluorescent lamp (CCFL) used for a light source of a backlight of a liquid crystal display (LCD) uses mercury gas, environmental pollution may be caused, response speed is low, color reproduction characteristics is low, and it is difficult to reduce weight, thickness, and size of an LCD panel.
On the other hand, light emitting diodes (LEDs) are environmental, have a high response speed of several nano seconds, are effective on a video signal stream, can be impulsively driven, have color reproduction characteristics of 100%, whose brightness and color temperature can be freely changed by controlling the amount of light of red, green, and blue LEDs, and have advantages on the reducing weight, thickness, and size of an LCD panel. Therefore, currently, LEDs are positively employed for a light source of a backlight of an LCD panel.
Generally, an LED backlight unit employing LEDs for a light source may be divided into an edge type backlight unit and a vertical type backlight unit, depending on a position of the light source. The edge type backlight unit has a bar shaped light source located on a side of light guide plate and emitting light to the front surface of an LCD via the light guide plate. On the other hand, the vertical type backlight unit has a flat fluorescent lamp (FFL) located below an LCD, having a size identical with the LCD, and emitting light to a front surface of the LCD directly. Generally, when the vertical type backlight unit is employed to an LCD having a wide area such as a large LCD TV, an entire area of the LCD is divided into a plurality of areas and an LED backlight unit driving LEDs separately from each other is employed for each divided area.
FIG. 1 is a schematic diagram illustrating a conventional LED backlight unit 100. Referring to FIG. 1, the LED backlight unit 100 includes a substrate 110 having a plurality of divided areas, a plurality of LEDs 111 of red, green, and blue, disposed on the substrate 110, and a plurality of LED drivers 121 driving the plurality of LEDs 111.
One of the plurality of LED drivers 121 is electrically connected to the plurality of LEDs to drive the plurality of LEDs of red, green, and blue, installed in one of the plurality of divided areas. Also, the one LED driver 121 includes a red LED drive circuit 121a driving red LEDs, a green LED drive circuit 121b driving green LEDs, and a blue LED drive circuit 121c driving blue LEDs. In FIG. 1, an arrow formed of a solid line connecting each of the plurality of LED drivers 121 with each of the plurality of divided areas of the substrate 110 shows a divided area including LEDs driven by a corresponding LED driver.
The conventional LED backlight unit 100 requires the LED drivers 121 whose number is identical with the number of the divided areas of the substrate 110. Accordingly, since a conventional LED backlight unit requires a large number of LED drivers, the number of electric-electronic parts for embodying LED drivers increases, thereby enlarging an area of a drive board for mounting the electric-electronic parts. Therefore, the manufacturing cost of LED backlight units increases and the size of LED backlight units increases. Also, since a conventional LED backlight unit has to control a large number of LED drivers, complication of control for driving LEDs increases.